1. Field of the Invention
The present invention relates to the field of vibration isolation and more particularly to vibration isolation of a payload of a missile during launch. Yet more particularly, the present invention relates to the reduction of vibrations caused by acoustic waves transmitted to a payload during passage through earth atmosphere and particularly passing through the sound barrier, or those reflected back from the initial ignition of the rocket engines on the ground
2. Description of the Prior Art
A number of vibration isolation devices have been proposed for use in reducing vibration transmitted from a launch vehicle to the payload during launch. One very successful device of this type may be found in a U.S. Pat. No. 5,947,240 assigned to the assignee of the present invention.
Such devices have concentrated on the reduction of mechanical vibration which is transmitted from the launch vehicle being propelled through the atmosphere by the rocket engines. Little or no effort has been exerted to reduce the vibration which occurs due the speed of the vehicle through the atmosphere particularly around the speed of sound where very large shock waves are produced. These shock waves cause the shroud around the payload to vibrate with considerable force and these vibrations are transmitted through the air in the shroud to the payload. It has been estimated that at the peak, the acoustic vibration produces about one half of the total vibration applied to the payload and accordingly, a need has arisen for acoustic vibration isolators.
The present invention overcomes the problem of acoustic vibration by causing an evacuation of the air surrounding the payload before or during launch so that when the vibrations from travelling through the atmosphere and the shock waves produced by the sound barrier occur, the medium for transmitting them to the payload is gone or reduced and the payload does not receive them.